We also increase the witness size for these types to account for the 3
extra bytes. The size won't be correct in all cases, but it is just an
upper bound in any case.
Since we never attempt to sweep an HTLC we offered with the preimage on
the remote's commitment, we never use the constant
AcceptedHtlcSuccessWitnessSize for weight estimation. Similarly, we
never timout an HTLC offered by the remote on our own commitment, and
don't need the constant OfferedHtlcTimeoutWitnessSize.
This commit is a step to split the lnwallet package. It puts the Input
interface and implementations in a separate package along with all their
dependencies from lnwallet.
